An Altcoin that follows the POS mechanism cannot have a halving mechanism like Bitcoin. You can only choose Altcoins with POS mechanism and limited supply such as Cardano (ADA), Polkadot (DOT), Avalanche (AVAX). Bitcoin's POW mechanism seems to be quite outdated and consumes a lot of energy, but in my personal opinion, POW is still the safest mechanism, and Bitcoin is still the top choice instead of trying to find an Altcoin has a mechanism similar to Bitcoin.